Insulin-like growth factor I receptor (IGF-IR, EC 2.7.112, CD 221 antigen) belongs to the family of transmembrane protein tyrosine kinases (LeRoith, D., et al., Endocrin. Rev. 16 (1995) 143-163; and Adams, T. E., et al., Cell. Mol. Life Sci. 57 (2000) 1050-1063). IGF-IR binds IGF-I with high affinity and initiates the physiological response to this ligand in vivo. IGF-IR also binds to IGF-II, however with slightly lower affinity. IGF-IR overexpression promotes the neoplastic transformation of cells and there exists evidence that IGF-IR is involved in malignant transformation of cells and is therefore a useful target for the development of therapeutic agents for the treatment of cancer (Adams, T. E., et al., Cell. Mol. Life Sci. 57 (2000) 1050-1063).
Antibodies against IGF-IR are well-known in the state of the art and investigated for their antitumor effects in vitro and in vivo (Benini, S., et al., Clin. Cancer Res. 7 (2001) 1790-1797; Scotlandi, K., et al., Cancer Gene Ther. 9 (2002) 296-307; Scotlandi, K., et al., Int. J. Cancer 101 (2002) 11-16; Brunetti, A., et al., Biochem. Biophys. Res. Commun. 165 (1989) 212-218; Prigent, S. A., et al., J. Biol. Chem. 265 (1990) 9970-9977; Li, S. L., et al., Cancer Immunol. Immunother. 49 (2000) 243-252; Pessino, A., et al., Biochem. Biophys. Res. Commun. 162 (1989) 1236-1243; Surinya, K. H., et al., J. Biol. Chem. 277 (2002) 16718-16725; Soos, M. A., et al., J. Biol. Chem., 267 (1992) 12955-12963; Soos, M. A., et al., Proc. Natl. Acad. Sci. USA 86 (1989) 5217-5221; O'Brien, R. M., et al., EMBO J. 6 (1987) 4003-4010; Taylor, R., et al., Biochem. J. 242 (1987) 123-129; Soos, M. A., et al., Biochem. J. 235 (1986) 199-208; Li, S. L., et al., Biochem. Biophys. Res. Commun. 196 (1993) 92-98; Delafontaine, P., et al., J. Mol. Cell. Cardiol. 26 (1994) 1659-1673; Kull, F. C. Jr., et al. J. Biol. Chem. 258 (1983) 6561-6566; Morgan, D. O., and Roth, R. A., Biochemistry 25 (1986) 1364-1371; Forsayeth, J. R., et al., Proc. Natl. Acad. Sci. USA 84 (1987) 3448-3451; Schaefer, E. M., et al., J. Biol. Chem. 265 (1990) 13248-13253; Gustafson, T. A., and Rutter, W. J., J. Biol. Chem. 265 (1990) 18663-18667; Hoyne, P. A., et al., FEBS Lett. 469 (2000) 57-60; Tulloch, P. A., et al., J. Struct. Biol. 125 (1999) 11-18; Rohlik, Q. T., et al., Biochem. Biophys. Res. Comm. 149 (1987) 276-281; and Kalebic, T., et al., Cancer Res. 54 (1994) 5531-5534; Adams, T. E., et al., Cell. Mol. Life Sci. 57 (2000) 1050-1063; Dricu, A., et al., Glycobiology 9 (1999) 571-579; Kanter-Lewensohn, L., et al., Melanoma Res. 8 (1998) 389-397; Li, S. L., et al., Cancer Immunol. Immunother. 49 (2000) 243-252). Antibodies against IGF-IR are also described in other publications, e.g., Arteaga, C. L., et al., Breast Cancer Res. Treatment 22 (1992) 101-106; and Hailey, J., et al., Mol. Cancer Ther. 1 (2002) 1349-1353.
In particular, the monoclonal antibody against IGF-IR called αIR3 is widely used in the investigation of studying IGF-IR mediated processes and IGF-I mediated diseases such as cancer. Alpha-IR-3 was described by Kull, F. C., J. Biol. Chem. 258 (1983) 6561-6566. In addition, about a hundred publications have been published dealing with the investigation and therapeutic uses of αIR3 in regard to its antitumor effect, alone and together with cytostatic agents such as doxorubicin and vincristine. αIR3 is a murine monoclonal antibody which is known to inhibit IGF-I binding to IGF receptor but not IGF-II binding to IGF-IR. αIR3 stimulated at high concentrations tumor cell proliferation and IGF-IR phosphorylation (Bergmann, U., et al., Cancer Res. 55 (1995) 2007-2011; Kato, H., et al., J. Biol. Chem. 268 (1993) 2655-2661). There exist other antibodies (e.g., 1H7, Li, S. L., et al., Cancer Immunol. Immunother. 49 (2000) 243-252) which inhibit IGF-II binding to IGF-IR more potently than IGF-I binding. A summary of the state of the art of antibodies and their properties and characteristics is described by Adams, T. E., et al., Cell. Mol. Life Sci. 57 (2000) 1050-1063.
Most of the antibodies described in the state of the art are of mouse origin. Such antibodies are, however, not useful for the therapy of human patients without further alterations like chimerization or humanization. Based on these drawbacks, human antibodies are clearly preferred as therapeutic agents in the treatment of human patients. Examples of human antibodies against IGF-IR are described in WO 02/053596. However, these antibodies have not been shown to benefit patients in need of antitumor therapy.
There is still a need for human antibodies against IGF-IR having convincing benefits for patients in need of antitumor therapy. The relevant benefit for the patient is, in simple terms, reduction in tumor growth and a significant prolongation of time to progression caused by the treatment with the antitumorigenic agent.